Matt's '92/'99 4X4 V8/4R70W swap!

[seth247]

Heres an excerpt from that article:

The 1998+ revision of the mlps sensor is not electrically compatible with a 1992-1997 pcm. 92-97 vehicles use a resistive multiplex setup to inform the pcm of the driver selected gear, 98+ vehicles use a "bullet proof" switch that has numerous normally open switches in parallel. You will notice is you have the wrong mlps sensor because the "old ones" have 8 pins, the "newer" ones have 12 pins. Make sure to properly calibrate the mlps after installation.

just checked mine, it is a 12 pin.

 

[CDW6212R]

Well that's not good. You found the other diagrams which helps a lot, but that MLPS issue is bigger. Let's hunt on the TCCOA site, to see what those Thunderbird guys do with later transmissions.

 

[CDW6212R]

I sent a message to a trusted member there. I think the easiest route will be to change the wiring harness for the engine/trans, and the MLPS. It looks like you will need to do that, or swap the PCM to 1998 and then have to deal with PATS.

 

[seth247]

I've been studying my two PCM pinouts.

If these are accurate, there were no changes at the PCM when they changed the trans harness. All the pins are the same at the computer.

However. The dtrs pins did change. My '96 diagram has one pin listed for the DTRS, pin number 64, circuit 199, labeled "transmission range sensor input"

my '98 diagram has 5, pins 3, 49, 50, 64, and 91. They are labeled, respectiveley, TR1, TR2, TR3, TR, and "sig return" which is a generic voltage supply for several sensors.

On my '96 diagram, pins 3, 49, and 50 are empty.

I think this is why I'm not shifting. The '96 was designed fo the resistive unit. Which would only require the one wire. Then they changed it to a much smarter bank or NO switches. Which needs the five wires which in combination can identify all the shifter positions more accurately than the resistive setup. Since it doesn't have to contend with resistor degredation or voltage irregularities.

 

[CDW6212R]

Yes, your thorough digging turned up the DTRS/MLPS issue. No one has tried to swap the 98+ trans into a 96/97 truck before, that I recall. Jamie may think of someone, his trucks used the early PCM's.

I think swapping the wiring harness will be the easier way to make it work, plus the older MLPS. I have a 97 trans I'd give you the sensor from, but it's an unknown. Try Karl for the wiring and the sensor, he'd be the best bet. I don't think you want to swap the PCM and buy a flasher just for the PATS. You can do that, what cam do you have again, any other engine changes?

 

[seth247]

Comp cam. Mid range power, beehive springs, forged rods and pistons.

The plans have always included a tune from James. I just didn't plan for it this early. So the xcal will be of future use.

Bu hopfully I can find a working early model sensor. And just run a few wires to the PCM. I won't bother the harness. The extra wires for the new style sensor won't interfere with anything. Those pins are empty on the old computer.

In fact now I look at it I can use one of the wires from the newer sensor cause it's in the same pin location I need. Might not even need to run wires. Just cut and payste.

I'll figure it out when I get a full set of diagrams for a 96.

 

[seth247]

ok got my diagrams for a '96 from wiring-diagrams.com. and they are of course great.

according to this there are only two wires on the older style resisitive mlps.(what does that stand for by the way?) the voltage supply, which for some reason they mark "sig return" even though its not. and the signal wire to the computer which goes to pin 64. they are even the same color as the wires i have now.

and they are at the same pin positions at the computer as the wires are in my harness.

so all i got to do is find an old style sensor and i'm gold. lets hope i can get one from the junk on Monday. The Dudes gonna have to pick it up with a fork lift for me to get it though, it has no wheels.


edit. sh*t this means i have to take my shifter arm back off again. dam spent two days on that. and im gonna have to drain the pan to re align it.

 

[410Fortune]

ask for a 96 Mustang DTRS

Autozone, MUCH cheaper then an Explorer DTRS, same part

been there done that!

 

[CDW6212R]

The MLPS/DTRS can be changed without pulling the pan or roll pin. Unbolt the two tiny hold down bolts and the big nut on the shifter arm etc.

Be sure to align the MLPS properly though, look at it closely. There are two lines which must line up when it's in neutral I believe.

Avoid the non Ford parts for that, the Autozone specifically have a high failure rate when brand new. I'd rather try any used Ford MLPS than a new parts store version. Go to them as a last resort.

That's good thinking about the wiring, just use the existing wires, and as you did check to see that they go to the right pins of the PCM.

 

[410Fortune]

just FYI the autozone part is the exact same part as the Ford part.....as is carquest, pep boys, Cragen and Napa......I could only find one DTRS, just in many different boxes and prices


I have a few laying around now if you need one LOL

 

[CDW6212R]

I just spoke with an expert who builds these 4R's for a living. He tests the sensor he get's from Autozone, and returns the bad ones. He has the proper Ford testing tool to check them, we don't. He buys several at a time, and sometimes returns half of them.

 

[seth247]

I got mine from main auto.

Strangley. It comes with a plug. With no wires. It's the same 8 pin pattern but the outside shape is the different. The instructions say to release the wires and terminals from the old plug an. Insert them into the new one. I thunk it's supposed to seal better than the own part. Plug looks more water resistant.

Anyway I gotta go strong arm my junkyard tomorrow.

Can you believe it, I've been there like ten times. And when I called he tried to act like he didn't have any v8 explorers!

Too damn lazy to pick the thing up so I could get at the sensor I guess.

 

[CDW6212R]

The new sensors are updated, the original parts didn't have enough sealing from moisture. So the parts store thing might be an improvement for that. If you have it and are ready to start the truck, you could try it. It's not hard to remove the wires from the OEM connectors. It sounds like they tried to make it incompatible, I wonder why.

 

[seth247]

I just gotta go get an oem 8 pin now.

I don't think my 12 pin has the same terminals. But I'll look at it tonight.

 

[seth247]

I decided to dismantle some connectors from the old v6 harness to use as terminals for the new oldstyle sensor plug. Got that put together.

 

[410Fortune]

Nice! I love junk yard wiring plugs, I collect them

My BII is a hodge podge of different wiring plugs, I wired my power dist box so I can take it out of the truck using two large square engine plugs, my power seats are using alternator wiring connectors from a 95 so I can take the seats out without cutting wires

these trucks can have only one owner, anyone else would just be scratching their heads!!

 

[CDW6212R]

Jamie, have you forgotten anything yet? Sometimes I look at something and wonder, did I do that.

 

[seth247]

That's the first time I've acually taken those connectors apart. It's super easy.

I will definitely start collecting the more useful ones myself.

I Have a question. Sometimes whn I'm Whatching the engine data on the laptop, the fuel Trims might go up to even +45%. It tries to die when I put it into gear and it sounds a bit diesley.

I'm thinking this is either because my maf is too close to the TB (about three inches) and not getting even airflow. Or because the flexible exhaust tubing I'm using as a temporary ypipe is letting air into the system and jacking with the o2 sensors.

Or do you think the computer maybe doesn't like my cam.

 

[CDW6212R]

If it comes down to the tuning not working or being stable as it should, I'd think the MAF is too close to the TB. Have James look at your data logging to see what he thinks.

 

[Jakee]

The LTFT or the STFT? I believe it's recommended to stay atleast 6" away from the TB.


Ford Fuel Trims



When you are at wot you should be in OPEN loop.

Short term trims at WOT display the fuel that you are commanding in the base fuel table

or cold fuel table if certain timers/ect temps are not met.



Example for Closed Loop Operations.



Short_Term_Fuel_Trims

ST trim = .86 Then the pcm thinks the mixture is too lean. ADD 14% fuel

To fix this you would add fuel…do this by increasing the MAF curve in that area.



ST trim = 1.14 Then the pcm thinks the mixture is too rich. Remove 14% fuel

To fix this you would remove fuel....do this by LOWERING the MAF curve in that area.



Long_Term_Fuel_Trims

LT trim = 1.14 Then the pcm thinks the mixture is too lean. ADD 14% fuel

To fix this you would add fuel....do this by increasing the MAF curve in that area.



LT trim = .86 Then the pcm thinks the mixture is too rich. Remove 14% fuel

To fix this you would remove fuel....do this by LOWERING the MAF curve in that area.